CAMBRIDGE, Mass. — In Philadelphia last spring, a man riding a city bus at rush hour injected heroin into his hand, in full view of other passengers, including one who captured the scene on video.In Cincinnati, a woman died in January after she and her husband overdosed in their baby’s room at Cincinnati Children’s Hospital Medical Center. The husband was found unconscious with a gun in his pocket, a syringe in his arm and needles strewn around the sink.Here in Cambridge a few years ago, after several people overdosed in the bathrooms of a historic church, church officials reluctantly closed the bathrooms to the public.

“We weren’t medically equipped or educated to handle overdoses, and we were desperately afraid we were going to have something happen that was way out of our reach,” said the Rev. Joseph O. Robinson, rector of the church, Christ Church Cambridge.

With heroin cheap and widely available on city streets throughout the country, users are making their buys and shooting up as soon as they can, often in public places. Police officers are routinely finding drug users — unconscious or dead — in cars, in the bathrooms of fast-food restaurants, on mass transit and in parks, hospitals and libraries.​The visibility of drug users may be partly attributed to the nature of the epidemic, which has grown largely out of dependence on legal opioid painkillers and has spread to white, urban, suburban and rural areas.Nationally, 125 people a day die from overdosing on heroin and painkillers, and many more are revived, brought back from the brink of death — often in full public view. The police in Upper Darby, Pa., have even posted avideo of another man shooting heroin on a public bus, and then being revived by Narcan, which reverses the effects of a heroin overdose, to demonstrate the drug’s effectiveness.Some addicts even seek out towns where emergency medical workers carry Narcan, “knowing if they do overdose, there’s a good likelihood that when police respond, they’ll be able to administer Narcan,” said Special Agent Timothy Desmond, a spokesman for the New England region of the Drug Enforcement Administration.